150. Prune unto the Lord, for He Hath Done Pride
In the verse, “Prune  unto the Lord; for He hath done pride,” it seems that “prune” is like “my strength and pruning.” This means that we should always prune and cut the thorns off of the Creator’s vineyard. And even when one feels that one is whole, and thinks that he has already removed the thorns, the verse concludes, “for He hath done pride.”
This means that He has seemingly created pride in this world, that man likes to be honest and true in one’s own eyes. And when one feels about himself that he has already removed the thorns and that he is a whole man, it is a kind of pride.
Rather, one should always examine one’s actions, and check them with ten kinds of examinations, and not rely on one’s temporary sensation, for this is only a kind of pride. It is as the verse says in the name of the righteous: “Ye are idle, ye are idle; therefore ye say: ‘Let us go and sacrifice to the Lord our God.’”
This means that He said to the children of Israel, “when you say, ‘Let us go and sacrifice to the Lord,’ and you feel that you are already willing to go and sacrifice yourselves on the altar before the Lord, it is like idleness and weakness, that you no longer want to work and constantly examine yourselves, to make you ready for this great work. This is why you think that you are already perfect in this servitude, as they interpret at the end of the verse, ‘for He hath done pride.’”
Zamru, in Hebrew means both sing and prune. In this case it is referring to the latter.